Electrical connector



Feb. 5, 1957 F H. w. EARL 2,780,792

ELECTRICAL CONNECTOR Filed Aug. 18, 1953 mmvrox HQERYCQ'. 5.421.

BY 515$ M,Mw t? T'TOEA/E Y6.

i l l I ELECTRICAL CONNECTOR Harry W. Earl, South Miami, Fla.

Application August 18, 1953, Serial No. 374,917

2 Claims. (Cl. 339-256) This invention relates to separable electricalconnectors. More particularly the invention relates to electricalconnectors for use in industrial applications where separable connectorsare required for equipment using heavy currents.

The present invention is for a connector of the type having two partsdesigned to be attached to the ends of two cables or conductors to bejoined, and having telescopically interfitting parts through which theelectrical connection is made. According to the present invention, thecontacting areas of the interfitting parts are extensive, and provisionis made for holding the surfaces in tight frictional contact with oneanother so as to reduce electrical losses and provide a good currentconducting path.

The primary object of the present invention is to provide an electricalcable connector which may be readily connected and disconnected, andwhich when connected will provide a large, tight surface contact thatwill conduct heavy amperage electrical currents without substantialheating, and which will be safe.

With this and other objects in view, the invention consists in theseparable connector as hereinafter illustrated and described andparticularly defined in the appended claims.

The various features of the invention are illustrated in theaccompanying drawings, in which:

Fig. l is aview in side elevation of the male unit of the preferredconnector;

Fig. 2 is a view in side elevation of the female unit of the connector;

Fig. 3 is a longitudinal sectional view of the two units in cooperatingengagement;

Fig. 4 is a horizontal sectional view of the female unit taken on lineIV-IV of Fig. 2, with the rubber handle omitted;

Fig. 5 is a view similar to Fig. 4 of a slightly modified constructionand with the expander shown in elevation and rotated 90 from theposition shown in Fig. 4; and

Fig. 6 is a horizontal sectional view of a modified form of the femaleconnecting unit.

The separable electrical connector of the present invention isparticularly adapted for connecting conductors which preferably are madeup in the form of a series of strands of wire twisted into a cable, andthe cable is covered with a good insulation, but may be otherwise used.As previously indicated, the connector is comprised of two partsdesignated as male and female units, and each is connected to a cableend to be joined.

Referring to Figs. 1 and 3, the male unit comprises a tubular metal body10 into which is fitted and permanently secured a longer tubular member12, thereby forming a plug element with a shoulder 13 intermediate itsends. The projecting end portion of the tube 12 has two or morelongitudinally-extending slits reaching from the open end to a pointnear the shoulder 13. In smaller connectors there may be but twodiametrically opposite slots, but in larger connectors I prefer toprovide three of them equally spaced around the tube. These slots giveStates Patent 0 the cable in the socket.

2,780,792 Fatented Feb. 5, 1957 radial resilience to the extension 12.The end of a stranded cable 18 from which the insulation has beenstripped is inserted into the opposite end of the assembly, and screws20 threaded through the walls of the concentric tubes 10 and 12 areprovided to firmly clamp this end of the cable inside the tube 12.

A rubber or rubber-like insulating grip 22 is frictionally fitted overthe tube 10 and is longer than the tube 10, so that the grip enclosesthe end of the cable 18 and only the slotted extension of the tube 12,projecting from the opposite end of the assembly, is exposed. The screws20 are accessible through openings in the insulating sleeve, andprojecting as they do into this sleeve, prevent the insulating sleevefrom stripping or sliding on the metal tube 10, but they are countersunkdeeply enough so that one cannot touch them. The end of the grip orinsulating sleeve which faces toward the slotted extension of theconnector is cupped out or recessed at 23, providing an endwisecompressible extension 23a at this end of the grip.

The female unit is shown more particularly in Figs. 2, 3 and 4. Thisunit is comprised of an outside tubular member 16 having a plug 24soldered or frictionally driven into one end. This plug is counterboredat the rear or outer end to provide a socket to receive the bared end ofcable 42. Screws 28, similar to screws 20. clamp Projecting forwardlyfrom the end of the body is an expander plug 34 which is bifurcated orslit longitudinally as indicated at 32 to give the expander resiliencein a radial direction. In smaller connectors the inherent resilience ofthe metal may be relied upon, but in some instances, an adjustableexpander, as hereinafter described, may be desirable. The expandertapers or bulges from the forward or left-hand end as viewed in Fig. 4to a point 36 of maximum diameter, and then decreases in diameter,terminating at a shoulder 38, the shoulder preferably having a slightrearward bevel. In Figs. 2 to 4 inclusive I have shown the expanderhaving its point of largest diameter approximately midway between theends, but in some instances, especially in larger connectors, this pointmay be close to the front end of the plug as shown in Fig. 5.

The female unit has a rubber or rubber-like insulating grip 40 thereonwhich is the exact counterpart of the grip 22, and the end whichconfronts grip 22 has a cavity 41, similar to 23, and a thin projectingflange 41a similar to 2311. This grip cooperates with the screws 28 inthe manner hereinbefore described as to screws 20.

The tube 12 has an outside diameter such as to provide a close fitinside the tube 16, and the bulge of the plug or expander 34 is suchthat it slightly spreads the extension 12 when the two parts aretelescoped together. The expander thus forces the exterior of the tube12 into parallel full surface contact with the interior of tube 15. Thetwo parts can be shoved together preferably with a twisting motion forthe shorter connections until the end of the tube 12 is opposite acavity 39 in the expander 34 with the tube 12 compressed between thetube 16 and expander 34 a beveled end 12a of the tube is flexed inwardlytoward the bottom of the cavity 39 to make a tighter connection.

When the two parts of the connector are pushed completely together, theextensions 23:: and 41a of the rubber grip contact and compress endwise,making a tight joint which is resiliently closed by the compression ofthe rubber.

With the construction outlined above, the connector members may bepushed into and pulled out of contact with one another for connectingand disconnecting the cables, and with the resilience of the connectionprovided by the slitted tube 12 and slitted expander 34, the par-ts areyieldably held in firm connection so that they provide a large area ofinter-facial contact, and friction will hold the, two,un its.against anyaccidentalseparation. lnothe i words, it requires a distinct use of atwisting force in order to connect and disconnect theconuectors. Theconstruction provides a good'electricalcontact so that when highcurrentdensitiesarepassed through the cable, there will be,substantially. no'heating or undue power loss in the connector. The plug34 is recessedwell back intothe tube 1.6;sothat initialtelescoping of vthe parts canbe easily and quickly accomplished, and the strong frictionbetween the parts. is broken before final separation takes place. If theconnector, after use,,becomes too loose, a screw driver or otherinstrumentmay be driven into the slot 32; to slightly spread theexpander, and thus increase the pressure with which it spreadsthe tube12 when the units ofthe connector-are forcedtogether.

In the construction shown inFig. 5, I have shown a modification of thefemale unit of the connector which may; be-desirable in some instances,and may be used in place of;the arrangement shown in Figs. 2m 4inclusive. In this view, 45 designates the tubular sleeve of the femaleunit with the expander plug body 46 driven or soldered intotone end. Ithas a reducedexpander 4-7 projecting forwardly through a part of thelength of the tube. The expander, which is bifurcated,has a reducedouter or forward end with a bulge 48close to the end, and behind thisthe expander is of reduced section, terminating at thebeveled shoulder49.

While the, resilienceof the expander may in smaller connectors beadequate, in larger connectors it may be desirable, to provide a meansfor adjustably spreading the-expander, and to this. end-I have a taperedscrew 50 threaded into a tapered socket in the end of the expander. Aslight turn of this screw will controllably spread the expander: toproduce the desired spreading of the tube 12 of the male member. Thisscrew can be adjusted without taking-the unit apart.

The expander plug 46 of Fig. 5 is preferably used with a long connectorand with this expander plug the beveled end'of the tube 12:is moved pastthe bulge 48 and against the shoulder 49 to make amore effective contactand a tighter connection ofthe parts.

In Fig. 6 is shown a modified form of expander plug 52 which has anexpanding bevel 54 with a slit 56 at its front end. At the end of thetaper is a bulge 58 behind which isacavity 60. From the rear end of thecavity the plug hasan inclined face, 62 back to a shoulder 64. The. plugof Fig. 6 is preferably used with a smaller connector and thediameter ofthe bulge 58is such that the end of tube 12 will:be'-1ocated opposite.the cavity 69.

mal ansL smale. p rts, of. he. onnector. The, e 12 has an inclined face65 which can make a tight connection with the expander bevel 62 if it isdesired to force the end of the tube 12 against the shoulder 64.

The preferred form of the invention having been thus described, what isclaimed as new is:

1. A separable electrical, connector of the character describedcomprising a male and a female unit, said male unit having a hollow.insulatedhandle, portion, a hollow metal tube within said. handleportionand extending outwardly beyond one endthereof, the outermost end portionof, said, extel fiionhaving its inside walls tapering outwardly, meansontheinner end of said hollow metal tube for electrical'connection to apower cable, the outwardly extending portion of the metal tube havingslots extending inwardly from the end thereof and in opposite walls ofthe tube, the female unit having a hollow insulated; handle-portion, ahollow, metaltube within said female handle, portionfor; rect ption. ofthe slotted end of the t u be;o f the male unit, an expander plugsecured withinthe-tube of; the female, unit intermediate the endsthereof, said expander plug having a rear base portion secured withinthefemale unit and a'forwardly extending portionv disposed wholly; inspaced relation to the surrounding metaltube of thefemale unit forengaging within the entering tube of themaleunit, said forwardlyextending,- plug portion; having a transverse slot extending inwardlyfrom its forward-end and a peripheral portion which isoflargest diameterintermediate the ends of said slot, saidperipheral portion taperinglongitudinally of said plug in,b o th directions from said portion oflargest diameter.

21. Theelectrical connector as defined in claim 1 wherein;thevslottedfmetal tube, extending from the male unit has resilientengagement with the, tube of the female unitcausing initialcompressionofthe slotted opening in the male tube as the male and femaleunits are assembled and the initialclearance between the greatestdiameter of the slotted expander plug of the female unit and the insideof the tube of the female unit is lessthan the untapcred thickness ofthe walls of the entering tube of the male unit.

References Citedin the file of this patent UNITED STATES PATENTS 611,000McElroy Sept. 20, 1898 2,015,590 Cavanagh Sept. 24, 1935- 2,-127,544 VonHoltz Aug. 23, 1938 2,246,670 Earl June 24, 1941 2;29l;793 Chandler Aug.4, 1942 FOREIGN PATENTS 146,781 Austria Aug. 10, 1936

